There is a desire to reduce carbon-based emissions from today's power supplies, while at the same time improving the fuel efficiency of the power supplies. In addition to providing power supplies that can do more work per unit of fuel, it would also be advantageous if the power supplies were capable of deriving energy from a variety of different fuels. A reduction in the size of the power supplies would also be consistent with the goals of improving fuel efficiency and reducing emissions, particularly with mobile power supplies.
One problem associated with conventional power supplies is that the power supplies have the best efficiency when they are running close to or at rated conditions. However, during many applications the full rated power of the power supply is not needed, and the power supply is therefore run at power levels that result in the inefficient use of fuel by the power supply, or the power supply produces excess energy that is wasted.
One attempt to improve the efficiency of a hybrid vehicle is disclosed in U.S. Pat. No. 4,199,037 of White that issued on Apr. 22, 1980 (the '037 patent). The '037 patent provides an electrically-driven vehicle with a turbine engine, a generator driven by the turbine engine, a battery for storing electrical energy, and motors for driving wheels of the vehicle. The motors are powered by electrical energy that can be obtained directly from the generator or from the battery. A controller turns the turbine engine on whenever the amount of usable energy stored in the battery drops below a first predetermined level. The '037 patent also discloses maintaining the speed of the turbine at a constant level to maximize its efficiency.
Although the hybrid system of the '037 patent may improve the efficiency of the disclosed vehicle, it may be less than optimal. In particular, the disclosed hybrid system of the '037 patent does not provide any means for storing energy other than a battery. When the stored energy in the battery rises above a predetermined level, the turbine engine is shut off and the only source of energy becomes the battery until the turbine engine is turned back on to drive a DC generator and recharge the battery. As a result, the system of the '037 patent may not allow for operation of the turbine engine at its point of maximum efficiency, and may not be able to provide energy as rapidly as desired in some situations.
The system and method of the present disclosure solves one or more problems set forth above and/or other problems in the art.